Automatic telephone system



J. E. os-rLlNE AUTOMATIC TELEPHONE SYSTEM Dec. 3, 1935.

Dec. 3, 1935. J. E. osTLlNE l I 2,023,239

AUTOMATIC TELEPHONE', SYSTEM original Filed Dec. 14, 19.53 y11 sheets-sheet 2 19a l o l f 0 fa Zoo Dec. 3, 1935. J'. E. osu-LINE 2 AUTOMATIC TELEPHONE SYST'EM Original Filed Deo. 14 1955 Dec. 3, 1935. J. E. osTLlNE AUTOMATIC TELEPHONE SYSTEM Dec. 3, 1935. 1, E OSTLINE l 2,023,239

AUTOMATIC TELEPHONE SYSTEM original Filed Deo. 14, 1955 11 sheets-sheet 5 Dec. 3, 1935.

J. E. OSTLINE AUTOMATIC TELEPHONE SYSTEM AI.: NNW

Original Filed Dec. 14, 1953 Dee, 3,. E935. J. E. osTLiNE AUTOMATIC TELEPHONE SYSTEM f a 4 a .4- y J f 7 )i a4; in da M w 59 i J/z/ Dec. 3, 1935. 1 E OSTLlNE 2,023,239

uToMATI TELEPHONE SYSTEM Original Filed DeC. 14 1953 ll Sheet rrr.'

Dec. 3, 935 J. E. osTLlN 2,023,239

4AUTOMATIC TELEPHONE SYSTEM origina Filed Dec. 14, 1933 11 sheets-sheet 9 11 sheets-smeet 10 .L E. osTLlNE AUTOMATIC TELEPHONE SYSTEM Original Filed Deo.. 14, 1933 Deus, 1935.

Dec. 3, 1935. J. E. osTLINE AUTOMATIC TELEPHONE SYSTEM 11 sheets-smet 11 Original Filed Dec. 14, 1953 type is Patented Dec.- 3, 1935 srA'rEs 2,023,239 AUTOMATIC TELEPHGNE SYSTEM John E. Ostlinc, Berwyn, Ill., assigner to ated Electric Laboratories,

Inc., cago, El., a

corporation ci Delaware Application December ld, 1933, Serial No. 702,@8 Renewed .l'uly 23, i935 25 Cla.

This invention relates in general to automatic telephone systems, but more inl particular to small systems suitedfor installation in towns or villages. An automatic telephone system of this generally known as a Community Automatic Exchange or C. A. X., and may have a capacity of about fifty lines, more or less. Usually the lines are party lines having either bridged or grounded ringing circuits over which such subscribers are signalled by means of code ringing. Provision is also made for trunking calls to and from distant exchanges. l

The object of the present invention is to provide a novel and improved all-relay community automatic exchange of the foregoing character.

One of the features of the invention relates to the all-relay finder-connector links for interconnecting the various'lines in this system.

Another feature of the invention. relates to the manner in which both the trunk lines and subscribers lines are connected to a nder-connector y link, especially the line and trunk hunting oper-1 ations of the finder and connector units relays.

Another feature of the invention relates to an all-relay allotter which preselects idle lnder-connector links and in which common relay testing equipment is provided for causing a calling line to-be connected to the preselected idle link.

Another feature of the invention relates to an improved lock pulsing arrangement for repeating the pulses received from a calling line.

Another feature of the invention relates to circuit arrangements whereby the lnder-connector link switches straight through cutting oi the local talking bridges on both incoming and outgoing trunk calls.

Another feature of the invention relates to a common all-relayv code interrupter and the circuit arrangements for selecting and connecting various code rings to called subscribers lines.

A further feature of the invention relates to an alarm sender which seizes a trunk line to the distant exchange when a case of trouble arises, and ,which transmits a series .of tones over the trunk line to identify the particular trouble.

These and other features of the invention will be apparent from the following detailed description of the invention.

Referring now to the drawings, 1 to 11, inclusive, there` is shown by means of the usual circuit diagrams sumcient of the apparatus in an automatic telephone system tov enable the invention to be readily understood.

Fig. 1 shows a group of finder group relays FGR for connecting the line conductors and test comprising Figs.

conductors of the various groups of lines and trunk lines to one'oi the iinder-connector allrelay links. The link shown is capable of interconnecting fifty lines. The groups of lines are divided into ilve groups oi ten lines each and are 5 designated as the 2t, su, tu, 5@ and 60 groups. Relays l22, i3d, #32,1% and l are call finder group control relays and operatively connect the test conductors of their respective groups to the link circuit shown. Relays such as relays E2G-lm, ttt-lill, leu-Btl, lEl-ll and itt-i are for connecting the line conductors of their respective groups to the link circuit. In the lower left-hand corner of Fig'. l is shown the line circuit LR of the nrst line in the 2ligroup. A plurality ci substations such as El l, dit?, 2id, and lill are diagrtically shown connected to this line. As will be seen, the line conductors oi this line, or line 2l, terminate in. armatures lil and itil of relay l@ in the 2te group, while the test conductor of this line terminates in armature i2@ of relay l2? in the ZQ-g group. The line conductors and the called test conductor extend by way of a three-conductor cable l5@ to the outgoing end of the link wherein these vconductors terminate in armatures on the connector group relay in the -group. In the upper left-hand corner of Fig.' l is sharm the t line circuit TIR, for the trunk line TR; shown in Fig. lll. As will be seen, this trunk line terminates in armature springs l it, lll and H2 of the under group relays t28 and B22. The trunlr line conductors are also` connected to the outgoing end of the link circuit in a manner similar to that described for line 2l. Lines 22, 23, it, 2?, 2t and 2l, and trunk lines 28 and 29, lndicated by the brackets, terminate in armatures controlled by the finder group relays in the 2tgroup for connecting such lines to the link circuit. In a similar manner the trunk lines and subscribers lines in the ttl-group and other groups are connected in a similar manner.

` Fig. 2Y shows a group of finder units relays FUR for connecting the line of any selected group to the control circuits in the link.

Fig. 3 shows a group of connector `units relays CUR forconnecting the link circuit to any particular called line in any called group as de= termined by the operated connector group relays.

Fig. 4 shows a group of connector group relays 50 CGR for connecting the outgoing end of the link to any line in any group. In the right-hand end of Fig. 4 is shown the line circuit of line 33 and a plurality of substatlons thereon. Line 33 ls connected to the incoming end of' the link as 55 2 shown diagrammatically by the three-conductor cable extending to armatures 451, 458 and 459, in Fig. 1. All of the trunk lines and all of the subscribers lines in allot the groups terminate in the outgoing end of the link in the manner illustrated by line 33.

Fig. 5 shows an all-relay lallotter for preselect- In the upper left-hand corner ing an idle link. of Fig. 5 are shown the link selecting relays LSR which control the selection of an idle link and which control the operation of the link connecting relay, such as 5|00, for connecting such link to the group selecting relays GSR in the common allotter. The group selecting relays GSR are operated to find the calling group while relay 550 is operated when the calling line is found by the nder units relay. In the lower left-hand corner of Fig. 5 is shown the allotterlcontrol relays ACR, which control different functions to be described hereinafter. Each group of lines has a start conductor, such as start conductor |31, extending from each group of line circuits to a terminal such as terminal 20 shown in thelower part of Fig. 5. The start conductor, correspond- 'ing to start conductor |31, of the 30-grou'p would terminate in the terminal 30, and the remaining rstart conductors oi the other groups would terminate in the correspondingly numbered terminals.. In the upper-right-hand corner of Fig. 5 is shown the connecting relay 5|00 of one of the link circuits. This relay connects the group selecting relays GSR to the finder group relays to the distant exchange when some trouble arises.

FGR of the selected link, and also connects cir-4 cuits ior controlling the line hunting operations of the link.

Fig. 6 shows a group circuit of the link.

.Fig 7 shows another group of relays in the control circuit of the same link.

Fig. 8 shows a further group of relays in 'the control circuit of the same link. Relay SI in of` relays in the control Fig. 8 is provided for connecting the counting relays 820 to B00, inclusive, to the connector group relays CGR, in Fig. 4. Relay S2 is provided for connecting the counting relays to the connector units relays CUR, in Fig. 3. Relay 890 is provided for connecting the common code interrupter CI to the counting relays.

v Fig. 9 shows an all-relay code interrupter CI, and a ringing machine RM.

Fig. 10 in its upper portion shows the trunk line TR which terminates in position 20` of the 20-line group of the link. This trunk line is connected by way of repeating coils RC and RCI and conductors |054 and |055 to the trunk cir-'- cuit TCat a distant exchange. This particular trunk circuit TR is connected to an alarm sender AS shown in Fig. l1.

Fig. ll'shows an alarm sender AS for transmitting a series of tones overthe trunk line TR 'Throughout the drawings numerous types of relays, well known in automatic telephone art, are shown. Slow-to-operate relays are shown having a full-black upper section. Slow-to-release relays are shown having a cross-hatched section. The weighted armature springs of vibrating relays are shown with a rectangular weight on their movable ends.

Although only substations having their ringers grounded for divided or grounded ringing have been illustrated in the drawings, it will be understood that substations having their ringers bridged across the line conductors may also be operated over the circuits shown.

sires to call subscriber 33|.

aoaacsa 1 Briefly the operation of the system is as folows:

When a calling subscriber initiates a call the testl conductor of lthe calling line is marked with callingpotential and the calling group is marked 5 in the common all relay allotter which operates to nd the calling group. When the calling group is found the allotter completes a circuit for. energizing the proper finder group control relay in an idle link previously preselected by the 10 allotter. The operation of the finder group control relay connects all of the test conductors of all the lines in the calling group to the nder units relays which now operate successively until the marked calling line is found. 15 When the calling line is found the allotter is operated to preselect another idle link and the vcalling line is connected to the control circuits of the link in use. The first digit transmitted by the calling subscriber operates counting re- 20 lays to operate the corresponding connector group control relay which connects all of the test conductors of the called group to the connector units relays of the link. The second digit reoperates the counting relays to operate the corresponding 25 connector units A.relay to connect the test conductor of the called line to the link control circuits. The third digit reoperates the counting relays to select the ringing code. It the called line is idle an all relay code interrupter controls 30 a ringing relay in the link over the selected code ringing conductor to transmit the selected ringing code to the called line.

v trunk lines in this group are successively operated to hunt for an idle trunk in this group. When an idle trunk line is found the link switches through cutting off the local talking bridges.

It will now be assumed that subscriber 2|6 de- 50 When the subscriber at substation 2|6 removes his receiver a circuit is completed for energizing line relay |12 over the following circuit: from ground by way of armature |18 and resting contact, through the winding of relay |12, over the lower talking conductor of line 2| through the subscribers substation loop comprising the receiver R, transmitter T, calling device CD, and over the upper -heavy talking conductor o! line 2|, armature |11, 00

and through the winding ot relay |13 to battery. Relay |12 at armature |19 disconnects conductor |56 'from the cut-off relay |1| at its resting contact and at its working contact grounds conductor |56 which extends by way of the threeconductor 65 cable |59 of Fig. 4 to busy the calling lineat the called terminals, at armature |80 connects the cut-off relay |1| to armature |29 by way of armature |14 to mark line 2| as a calling line in the finder group of relays. At armature I8| relay 70 |12 grounds start conductor |31 by way of armature |15 and resting contact, thereby marking the group in which the callingline is associated in the relay allotter. Responsive to relay |12 grounding the start conductor |31 a circuit may 75 as just described and 40' be traced for energizing relay 581 from grounded armature |8|, armature |15 and resting contact, conductor |31, terminal 20, resistance R2, armature 5004, and through the lower winding of relay 581 to battery.

At the time this call is initiated the link selecting relays LSR in Fig. 5 have preselected the rst relay link. vSince one or more links are idle, the all link busy relay 588 is energized over the common all link busy conductor 629 from ground at the idle link circuits. One of these circuits may be traced from armature 626 and resting contact,

armature 506, springs 645 of busy key BK, cornmon to all link busy conductor 629, and through the winding of all link busy relay 588 to battery.

vRelay 588 is maintained energized from ground from the idle link circuits and therefore only deenergizes at a time when all of the links are busy. Relay 588 at armature 599 prepares a cir.- cuit for the link connecting relays, at armature 5000 prepares a point in the circuit to the link selecting relays LSR, and at armature 500| completes a circuit for energizing relay 585 as follows: grounded armature 500| and Working contact, through the winding of relay 585, through armatures 536, 530, 524, 5|8, and 5|I, and through the lower Winding of relay 50| to battery and in multiple therewith through the associated resistance to battery. Relay 50| is also maintained energizedover this circuit as long as the first link is preselected. Link selecting relay 50| at armature 501 prepares a point in the circuit for operating the link connecting relay 5| 00, at armature 509 prepares a point in the circuit extending to the guard conductor 8 i5, at armature 5|0 prepares a circuit for the second link selecting relay 502, and at armature SI2 opens a point in the circuit of link selecting relay 506.

Since the rst link is the link preselected, due to link selecting relay 50| being in energized position, the energization of start relay 581 completes, in this case, the circuit for energizing the link connecting relay 5|00 as follows: from ground by way of armatures 595, 599, 593, .and 501, and through the winding of relay 5| 00 to battery. At armature 596 relay 581 completes a circuit by Way of armature5002 for energizing relay 59|, at armature 591 prepares a point in the circuit for grounding the guard conductor 8|6 so as to transfer the call to the next idle link if the calling line is not found withina predetermined time, and at armature 598 completes a circuit through its lower winding independent of armature 5004. Relay 59| operates and closes the circuit to relay 590. Relayl 590, after an interval, energizes and at armature 5005 completes the circuit for energizing relay 589 as follows: armature 596, armature 5005 and working contact, and through the winding of relay 589 to battery. At armature 5002 relay 589 opens the circuit of relay 59| which deenergizes; at armature 5003 prepares a point in the circuit for the guard lead 8|6, and at armature 5004 opens the original energizing circuit of relay 581. Relay 59|, upon restoring, causes its weighted spring 5008 to vibrate alternately opening and closing the circuit of relay 590. Due to its slow release action, relay 590 remains operated during the vibrations of spring 5008. Relay 5|00, upon energizing over the above traced circuit, at armatures5|02, 5|03, 5|05 and5|06 prepares circuits for operating the finder group control relays shown in Fig. l. At armature 5|0| relay5l00 completes a lcircuit for energizing relay 549 as'follows: from ground by Way of armature 5|0|, armature 516 from ground by way of 30-line group subscribers.

and resting contact, and through the winding of relay 549 to battery. At armature 5 08 relay 5|00 prepares a circuit for one of the finder group line relays of the nder group FGR, shown in Fig. l, at armature 5| 01 prepares a circuit for starting the hunting operation of the finder units relays FUR, shown in Fig. 2; at armature 5|09 prepares a point in the circuit for the common line test relay 550, and atar-mature 5| |2 connects ground to conductors 2|4 and |88 in order to provide locking ground for the nder group control relays and for the nder unit relays.

Relay 549, upon energizing. at armature 519 prepares a locking circuit for relays GSR, at armature 580 circuit for operating the nder units relays, and at armature 58| closes the vstarting circuit for energizing the group selecting relays, and in this case closes a circuit for energizing the first group selecting relay 543 as follows: ground by way of armaturev 58|, armature 511 and resting contact, armatures 513, 568, 563, 558, and 553 and their resting contacts through the Winding ofl relay 543 to battery. Relay 543 at armature prepares a point in the circuit for energizing finder vgroup control relay |22; at armature 552 completes a locking circuit for itself, at armature 553 opens a point in its original energizing circuit and closes the circuit for relay 544; and at armature 554 connects battery through the upper winding of group test relay 548 to the finder start conductor |31 which is grounded in response to a call from any subscriber in the 20line group.

The group selecting relays 543 to 541, inclusive, are slow to operate relays which only operate after a short interval and close their own locking circuits through their inner upper armatures before operating their remaining armatures. As-

the group selecting suming for the time being that some other sub-y opens a point in the l 544 to battery. Reny 544 55S opens the locking circuit of the rst group selecting relay 543 which Will be energized after an interval, at armature 551 completes a locking circuit for itself from grounded armature 519 by way of armatures 51|, 566, and 56|; at armature 550 opens its original energizing circuit at its resting contact and at its working contact closes the circuit for the third group selecting relayv 545; and at armature 559 connects the group test relay 548 to the finder start lead common to the In the same manner as just described relays 545, 546 and 541 operate in sequence each unlocking the preceding group selecting relay and connecting the nder start lead of the group with which they are associated to the upper winding of relay 548 until the calling line group is found or the last group is reached.

When the calling line group is found ground 'over the start lead, such as lead 31, completes the circuit for energizing the group test relay 548 through its upper Winding. Relay 548, upon energizing, at armature 511 opens the energizing circuit to the next succeeding group selecting revcircuit to relay 544. The group lay before such group selecting relay operates and closes its locking circuit; at armature 518 opens the circuit to the slow to release relay 549, and at armature 518 completes its locking circuit from grounded armature 5|0|, armature 518, armature -511 and its working contact, and through the lower winding of group test relay 548 to battery. At amature 515 group test relay 548 completes the circuit for energizing the selected finder group control relay, in this case relay |22, as follows: from grounded armature 515, amature 510, 565, 550, and 555 and their resting contacts, armature 55|, armature 5|02, group cut-in conductor |82, and through the winding of finder group .control relay |22 to battery. Relay |22, at armature |25 completes its own locking circuit from grounded conductors |88 and 2|4 and at armatures |23 and.

and through the winding of cut-off relay |1| to battery.

In the allotter in after an interval and at armature 519 opens the locking circuit of the energized group selecting relay, in this case relay 543, at armature 580 completes a circuit for operating the nder units relays of Fig. 2 in their hunting operation, and at armature 58| removes one of the multiple locking grounds from the lower winding of relay 548, which, however, is maintained energized from grounded amature 5|0|. Group `selecting'relay 543 deenergizes, and at armature 55| opens the original energizing circuit of relay |22 and at.

armature 554 opens the original energizing circuit of relay 548. It should be noted that dueto the slow to operate action of the group selecting relays, relay 544` did not have suicient time to operate and close its locking circuit before the group test relay 548, upon uding the calling group, energizes and at armature 511 opens the test relay 548, therefore, energizes when the group in' which the calling line is located is found, and at armature 511 opens the energizing circuit to the succeeding group selecting relay before such group selecting relay is fully energized.

As soon as relay 549 deenergizes the circuit for energizing the first nder units relay 2|0 may be traced as follows: from ground by way of armature 5|0|, armature 516 and working contact, armature 580, armature 583 and resting contact, armature 5|01, conductor 2|,3 by Way of armatures 2||, 22|, 23|, 24|, 25|, 28|, 21|, 28|, 29|, and 20| and their resting contacts, and through the winding of relay 2 I0 to battery. The nder units relays are also slow to operaterelays :and operate in a manner similar to that described for the group selecting relays in the allotter. At armature 2|2 relay 2||'| completes its locking circuit from grounded conductor |88 by way of armatures 203, 293, 283, 213, 263, 253. 243, 233, and 223. At armature 2|| relay 2|0 opens its original energizing circuit after its locking circuit is closed, and connects the grounded start conductor 2|3 to the second finder units relay 220. At armature 2|5 relay Fig. 5 relay 549 deenergizes 2|0 `prepares a point in the circuit for operating the nder group line relay having its circuit prepared by its associated energized nnder control relay, and at armature 2|8 prepares a circuit for the common Aline test relay 550 in the 3' allotter. In case the calling line is 2|, 3|, 4|, 5|, or 8| the operation of armature 2|8 completes a circuit for energizing the line test relay 550 in the allotter. However, in order to describe the hunting operation of the finder units relay 10 it will be assumed for the time being that some v line other than the line mentioned is calling.A In this case the second finder units relay 220' is operated from grounded conductor 2|3 by way of armature 2H and its working contact. At 15 armature 222 relay 220 completes its own locking circuit by way of armatures 233, 243, 253, 263, 213, 283, 293, and 203 to grounded conductor |88. At armature 223 relay 220 opens the locking circuit-of the rst finder units relay 2|0 zo to cause its deenergization; at armature 22| and its working contact prepares the energizing circuit for the third nder units relay 230 which circuit, however, is only completed upon the deenergization of the first nder units relay 2|0 25 at armature 2|| and its resting contact. At armature 225 relay 220 prepares the circuit to the finder group line relay having its circuit prepared by its associated nder'group control relay, and at armature 228 preparesa circuit for the 'common line test relay `550 in the allotter. The firstlnder units' relay 2|0 after an interval deenerg'iz'es and at armature 2|8 opens the previously prepared circuitfor thel common line test relay 550, and at armature 2li completes the circuit 35 for energizing thethird finder units relay 230.

`Injthe same manner as just described the remaining finder units relays operate in sequencel each preparing a circuitl to the preceding nder units relay and extending the test lead of the line with which they are associated to the winding of the common line test relay 550 until the calling line ,is found. l

When the calling line is found battery through the winding of cut-off relay of the calling line 45 will be connected to conductor 299 for energizing the common line test relay 550 and the subscribers cut-off relay in series. Since line 2| in, this case is the calling line it will be remembered that finder group control relay |22 has been energized and locked in energized position to prepare the circuit for the finder group line relay |20 and to connect battery from the winding of cut-off relay |1| to conductor |91 by way of armature |29. Therefore, when the rst finder 55 -unit relay 2|0 energizes and operates its-armature 2|8 'the circuit for energizing the common line test relay 559 in series with the subscribers cut-off relay |1| is completed. This circuit may be traced as follows: From ground through the 60 lower winding of relay 550, armature 5|09, conductor 6|9 to conductor 299, armature 2|8, conductor |91, armature |29, armature |80, armature |14, and through the winding of cut-off relay |1| to battery. Relay 550 energizes before the 65 second finder units relay 220 has had sufficient time to fully operate and accomplishes the following functions: at armature 583 and its resting contactv relay 550 disconnects ground from conductor 2|3 to prevent the next finder units relay, in this case relay 220, fromv fully operating, and at its'working contact completes a locking circuit through the upper winding of relay 550 from grounded armature 5| 0| and armatures 516 and 580. At armature 584 -relay 550 completes a 75 group line relay of amature i at armature |16 maintains its circuit closed indef of line relay |12. at armature |14 operated position.

pendent of armatures |80 and |14, at armature |11 disconnects relay |13 from the upper line conductor, at amature |18 completes a circuit for energizing relay |10 andl opens the circuit opens a point in the original energizingv circuit of cut-oif relay- |1| and at armature |15 disconnects ground from start conductor |31. Line relay |12, upon deenergizing, at amature |19 disconnects direct" ground from conductor |56 at its working contact and` at its resting contact substitutes the 'groundthrough the lower winding of line test relay 550 so as to maintain conductor |56' grounded to busy the line at the called terminal.

Finder group line over the above traced circuit, at armatures |21 and |28 completes a circuit for energizing line relay 690 in Fig. 6, over thei'ollowing circuit: from ground through the winding of line relay 690, resting contact and amature 664, conduc tor 219, amature .2|6, conductor |99, armature |21, through the talking conductors including the calling subscribers loop to conductor |86, armature 2|1,* conductor 269, armature 662-' and resting contact, and through the winding of relay 692 to battery. Line relay 690, upon energizing, at armature 69| completes a circuit for energizing impulse relay 640 as l'ollows: ground by way of amature 69|, armature 633, resistance 643, and through the winding of impulse relay 640 to battery. The circuit for energizing slow to release relay 600 may be traced from grounded amature 69| through the normally closed springs controlled by amature 634, and through the winding of relay 600 to battery. Impulse relay 640, upon energizing, atarmature 64| short circuits armature 633 to maintain the relay energized, and `at armature 642 prepares a point in the circuit for maintaining relay 600 in Relay 600, upon energizing, at armature completes an obvious circuit for energizing slow to release relay 6|0, at armature 602 connects direct ground to conductor 299, thereby connecting direct ground instead of ground through .the lower Winding of relay 550 to conductor |56 in order to maintain the calling line busy to other subscribers; and at armature,

083 connects ground through the normally closed springs controlled by armature 601 to conductor 2|9 to maintain the ilnder.` group line relay |20 in energized position. Relay 6| 0, upn energizing. at amature 6|| grounds conductor 2|4 to maintain the locking circuit o f the operated finder control relay |22 and the locking circuit of the operated finder units relay 2|0. At armature 6|2 relay 2|0 prepares a point in the energizing circuit of the trunk test relay 660, at armature 6| 3 completes an obvious energizing circuit for relay 620 through its-A lower winding and also completes a circuit by way of armatures 666 and 018 through the upper winding of relay 630 for energizing the latter relay, at amature 6|4 pre- Relay |10, upon energizing,

relay |20, upon energizing armature |28,

vcalling subscribers loop over the following cir- .cuitz from dial tone by way of armatures 62|,

l66|, and 68|, conductor 106, armatures 192 and 193, conductor 108, resting contactand arm'ature 612, through the tone condenser TC to conl0 ductor 693, through the talking condenser, resting contact and armature 664, and thence over the circuit previously traced through the calling substation loop. At armature 622 relay 620 connects a multiple ground to conductor 2|4 to l5 maintain the nder group control relay and -nder units relay in energized position, at armature 623 prepares the circuit for energizing the series relay 650, as well as preparing' an impulsing circuit Vto the counting relays; at armature 20' 624 prepares a point in the locking circuit for busy relay 610, at amature 625 connects ground to conductor 329 to prepare locking circuits for a number of relays, and at armature 621 groundsl conductor 141. At amature 626 and its'resting 25 contact relay 620. removes one of the ground connections from the common all link busy conductor 629 and at its working contact grounds guard conductor 6| 6 to cause the allotter to preselect another idle link. Relay at amature 63| connects. battery through resistance 609 to talking conductor 239 by way -of armature 662 in order to improve the impulsing circuit, at armature 632 opens a point in the circuit for energizingvthe connector group line relays, at larmature 633 opens the original energizing circuit oi impulsingrelay640,which,how ever, is held energized through its own amature 64|, and at amature 634 completes a new circuit for maintaining relay 600 energized as follows: 4o from ground by way` of armature 661, amature 642 and working contact, amature 634 and work- 'v ing contact, and through the winding of relay 600* to battery. At amature 635 relay 630 prepares -a further point in the impulsing circuit to the t5 counting relays, at armature 636 prepares a point in its own locking circuit throughits lower winding, at amature 631 prepares a point in the operating circuit for the counting relays, at armature 633 prepares a point inthe circuit for 50 -to battery. At armature 593 relay 566 opens the 60 circuit to the link connecting relay 5|00 which thereupon deenergizes after an interval, and at amature 594 'completes a circuit from grounded amature 596 for energizing the relay 59|". .Link

selecting relay 502, upon energizing, at amature 65 l5|3 prepares a circuit for the link connectingk relay in the second link similar to link connecting relay 5|00, at amature '5|4 opens a point in the circuit for grounding the-guard conductorassociated with the third link, at armature 5 I5 prepares 70 a point in thecircuit for grounding the guard lead 6|6' associated withthe second linkin case the call is not completed,'at amature 5|6 connects guard lead 6|6 associated with the second link to the upper winding of the third link 630, upon energizing, 30 l v selecting relay 503 to prepare `for the energization of the latter relay as soon as the guard lead 6|6 is grounded, at amature 5|1 completes a locking circuitior itself through the lower winding over the previously traced locking circuit extending fromv grounded armature 500| through the winding of relay 585, and at amature 5| 8 opens the locking circuit of the first link selecting relay Link selecting relay 50|. upon deenergizing, at armature 508 prepares a point in the circuit for grounding guard conductor 6|6' in case the call is not completed; and at amature 5|2 prepares a point in the locking circuit for the sixth link selecting relay 505, and at armature 5|0 opens the original energizing circuit of relays 502 and 585 which now deenergize. Relay 5|00, upon deenergizing, at armatures 5|02 and 5|06 opens the circuits extending to the finder group control relays, atarmature 5|0| opens the locking circuits of relays 548 and 550, thereby causing the deenergization of the latter relays, at armature 5I08 disconnects ground at armature 582 from y the conductor 2|8 grounded at-armature 603, and at armature 5I I2 disconnects one of the multiple grounds fromconductor 2|4.

At armature 584 relay 550, upon deenergizing, opens the circuit through the upper winding of start relay 581 and the latter relay now deenergizes in-case no other line in line group 20 is calling. Group test relay 548 at armature 515 opens a further point in the circuit of the finder group control relay |22, at armature 516 again prepares the circuit for relay 548, and at armaturey 511 again prepares the circuit for operating the group selecting relays. Relay 59|, upon energizing over the above traced circuit, operates its vibrating arm 5008 and closes an uninterrupted energizing circuit to relay 590 from grounded armature 598.

In case the second link is busy ground on the guard lead 6|6' closes 'a circuit for energizing link selecting relay 503 and relay 586 in series as follows: from grounded link conductor 6|5, armature 5|6, through the upper winding of link selecting relay 503, and through the winding of relay 58 8f.tobattery. In the same-manner as just described forcthe second link selecting relay 502 thelinkfselecting relays 503, 504, 505 and 506 operatetinvsequence opening the locking circuit to the preceding link selecting relay andconnecting the guard lead of their associated link to the suc'- ceeding'link selecting relay until an idle link is found or all links become busy.

In case no other call is waiting start relay 581' deenergizes and at armature 598 opens the circuitof relays 59|, 590 andl589. Relay 588, upon deenergizing, when an idle` link is found, at armature 583 prepares a point in the circuit for en- -ergizing the linkconnecting relay similar to link connecting relay 5|00 in the secondA link. .However, should another call be waiting lthe circuit through the lower winding ofrelay.. 581 .is still maintained by way of the startconductor similar v to startconductor |31 and the grounded resistancessuch as R2, R8 or R4 and does not, therefore, restore. In this case when relay 588 deenern gizes said relay at armature 583 will complete the circuit for energizing the link connecting relay similar to relay 5|00, and at armature 584 opens the circuit to relay 58| causing the weightedY spring 5006 to vibrate and interrupt the circuit to relay 590. The link connecting relay similar to relay 5|00 to the idle link now operates. and

closes a circuit to'l relay 548 to cause the operaing contact, armature described. The link connecting relay, which, however, isv

tion of the allotter in the same manner as previously described.

In'case the calling line is not found within a predetermined time, the timing arrangement controlled by relays 589, 580 and 59| will be operated to cause the allotter to select another idle link. In this case if the calling line has not been found by the time,y the weighted spring 5006 ceases its vibrations relay 590will restore and at armature 5005 open the circuit to relay 589 at its working l0 contact and at its resting contact completes a circuit for energizing link selecting relay 502 and relay 586 in series as follows: from ground by way oi armature 596, armature 5005 and resting contact, armature 5003, armature 5000 and work- 15 581, armature 508, armature 538', guard lead 6|6, armature 5|0, through the upper winding of relay 502 and through the winding of relay 586 to battery. Relays 586 and 502 operate to cause the allotter to preselect an 20 other idle link in the same manner as previously such as 5|00, will deenergize in response to the operation of relay 588 in order to open the circuit extending to the relays inthe link and to the relays in the 25 allotter.

In case all of the links become busy ground will therefore be removed from the common all link busy conductor 628 with the result that all link busy relay 588 will deenergize. At arma- 30 ture 599 relay 588 opens a point in the circuit for energizing the link connecting relays, such as 5|00, at armature 5000 opens a point in there w :ir.Ur cuit for grounding the variousguardfcnductors at its working contactand at its resting contact 35 prepares a circuit for operating the all link busy meter relay ALB, and at armature 500| and working contact opens the locking circuit to the link selecting relays and relay 585, and at'its resting contact completes the circuit for energizing re- 40 lay 59| as follows: from ground by way of armature 500| and resting contact, armature 5002, and through the winding of relay 59| to battery.

Relay 59|, upon energizing, at spring 5006 again completes the circuit for relay 580 andthe lat- 45 ter relay at armature 5005 again completes the circuit for relay 588. Relay 589, upon energizing, at armature 5002 opens the circuit to relay 59| and at armature 5003 prepares a circuit for the all link busy meter relay ALB. Relay 59|, 50 upon restoring causes its-weighted reed spring 5006 to vibrate and intermittently interrupt the circuit of relay 590. Relay 590 does not restore l immediately due to its slow releasing action, but

.-armature 5005 relay 590 opens the circuit of relay 589 at 'its working contact and at its resting contact completes the circuit for operating the all link busy relay ALB as follows: from ground by way of armature 500| and resting contact, armature 5005 and resting contact, armature 5003, armature 5000 and resting contact, and through the winding of relay ALB to battery. Relay ALB operates over this circuit and operates the meter M to registeran all link busy condition. After an interval slow to release relay 589 deenergizes, at armature 5003 opens the circuit through the all link busy relay ALB, and at armature 5002 again completes the circuit for relay 58|. Relay 59| again operates and the foregoing cycle of operations of relays 590, 588, and 58| continue until an idle link becomes available.

When a link becomes idle ground is again conaoaaase i nected tothe common conductor 323 to energize the all link busy relay 503. At armature 500| and resting contactA relay 530 opens the circuit to relays 589, 550, and 59| allowing them to restore in case no call is waiting, and at its workingcontact completes a circuit for energizing the link selecting relay 50| and relay 585' in series.

as follows: from ground by way of amature 500| and Working contact, armature 582 through the upper winding of relay 50 and through the windarmature 500| and working contact, through the winding of relay 585, through armatures 536, 530, 524, |8 and 5| |through the lower winding of relay 50| to battery. At amature 501 relay 50| prepares a circuit to the link connecting relay 5I00, at armature 509 prepares a point in the circuit for grounding the guard lead 5|5, andat.

armature 5|0 connects guard lead 5|5 to the second link selecting relay 502. Relay 585 at armature 592 opens a point in the original energizing circuit of relay 50|. In case the first link is busy ground will be encountered on the guard lead 5|5 and the second link selecting relay 502 and relay 585 will operate in series in the manner previously described. At armature 5|1 relay 502 closes its locking circuit through its lower winding in series with relay 585, at armature 5| 3 prepares the circuit for the link connecting relay in the second link and at armature 5|5 connects the guard lead 5| 5' of the second link to'the upper winding of the third link selecting relay 503. At armature 5| 8 relay 502 opens the locking circuit of relay 50| allowing such relay to deenergize. If the `second`link is busy ground on the guard lead 5 5' completes the circuit for energizing the third link selecting relay 503 in a similar manner. Relays 503. 504, 505 and 505 operate in sequence opening the locking circuit` to the preceding link selecting relay and connecting the guardl leads of their associated links to the upper windings of the succeeding link selecting relays until an idle link is found. When an idle link is found the absence of ground on the guard lead prevents further operation of the link selecting relays and opens the circuit oi' relay 585 which thereupon deenergizes. Relay 535, upon restoring, at armature 5,94 opens the circuit to the time control relay 59| and at armature 593 prepares a point in the circuit for the link connecting relay of the preselected idle link.

When lthe calling subscriber vhears the well known dial tone such subscriber will dial the first two digits of the called number in accordance with the called subscribers line and then the third digit in accordance with the ringing code assigned to the desired subscriber on this line. In response to the operation ofthe calling device CD at the calling line for the rst digit the circuit extending over the heavy talking conductors to relays 590 and 532 is interrupted in accordance with the digit dialed. Whenever the dialling circuit is interrupted line relay 300 deenergizes and at armature 59| opens the circuit of the impulsing relay 540. Impulsing relay 540 therefore follows the impulses and at armature 54| opens a point in its own locking circuit, at amature 342 and wormng contact opens the circuit ci' slow to release relayi550 which remains in energized position during the impulsing period due to its 'slow releasing characteristics and at its resting contact completes a circuit for energizing 5 the series relay 550 as follows: from ground by way of armature 551, armature 542 and resting contact, amature 523, and through the winding of relay 550 to battery. Relay 550 is alsova slow to release relay and maintains its armatures atv tractedthroughout the impulsing period. Relay 4 550, upon energizing, at armature 55| connects battery Athrough resistance 500 in shunt of the battery through the relay 532 to improve the impulsing circuit, at armature 552 completes a circuit for energizing relay 1| 0, at armature 553 completesa locking circuit by way .of armature 536'through the lower winding oi relay 530 and grounds conductor 591 by way .of armature 531 in lorder to operate the counting relays shown in Fig.4 8 andat armature 554 completes a circuit for energizing relay SI in Fig. 8 as. follows: from ground by way of armature 538 and working contact, armature 554 and working contact, amature 61|, conductor 105,A armature 132, arm- 25 ature 19| and resting contact, conductor 155, and through the winding of relay SI to battery. 'I'he circuit for energizing relay 1 i0 may be traced from grounded armature 551, armature 342 and lresting contact, armatures 523, 535 and 552, conductor 133, armature 103 and resting contact, and through the winding of relay 1|0 to battery. Relay SI at armature 805 grounds conductoi 123 to provide a locking circuit 'for the impulse counting relays and at armature 305 completes a locking circuit for itself which may be traced from grounded armature 525, conductor 323. armature 103, conductor 15|, armature 813, armature 805 and through the winding of relay SI to battery. Relay Si at its remaining armatures 40 connects up the connector group control relays CGR, relays 150, 150, and 300 to the impulse counting relays. Relay 1|0 at armature 1|| prepares a circuit for reenergizing impulsing relay` 540 when the line relay 530 is again energized, at armature 1|2prepares a point in the circuit for testing the/y busy or idle condition of the called line, and at armature 1|4 prepares a circuit i'or energizing relay 100. Relay 100 will not energize at this time because its lower winding conductor 331.

When line relay 590 reenergizes afterthe termination of the nrst impulse a circuit may be traced for reenergizing impulsing relay 540 as follows: from grounded armature 59|, conductor 125. armature 1| I, resting contact and armature 60 10|, conductor 125, and through the winding of impulslng relay 540 to battery. At armature54l impulsing relay 540 again completes its lockingcircuit through resistance 543, at armature ,542 and resting 'contact opens the circuit of series 65 relay 350 and also removes ground from conductor 133 and at the working contact of armature 542 againk completes the circuit for relay 500 before-the latter relay has had time to deenergize. In response to the removal of ground from conductor 133 the short circuit around the lower winding of relay 100 is removed with the result that relay 100 now energizes in series with relay 1|0 as follows: from ground by way of armature 353. armature .331 and working contact,

'f pares conductor 891, resting contact and armature 122, armature 1I4 and working contact, through the lower winding of relay 188 and through the winding of relay 1I8 to battery. Relay 1I8 is maintained energized over this circuit. Relay 188, upon energizing, at armature 18| and resting contact opens the previously traced energizing circuit for relay 848 which is now held energized over its own locking circuit, and at its working contact prepares a point in the circuit for again reenergizing the impulsing relay 848 after the next impulse. At armature 183 and resting contact relay 188 opens the original energizing circuit of relay 1|8 and at its working contact preacircuit for energizing relay 128 through the upper winding of relay 108. At armature 184 relay 188 connects grounded conductor 891 to conductor 1I8 to energize counting relay 818 vby way of armature 88|.

At armature 81| relay 818 preparesa point in the circuit to the first connector unit relay 3|8, at armature 812 prepares a point in the circuit to the seventh connector units relay, and also prepares the circuits for the finder group relay 432 and relay 888, atarmature 813 temporarily opens the locking circuit of relay Si which is without effect during the impulsing period, at armature 814 prepares the circuit for energizing counting relay 888, at armature 815 completes a locking circuit for itself, at armature 818 opens a point in the locking circuit of relay 838, at armature 811 completes a circuit for energizing counting relay 888, at armatures 818 and 819 prepares circuits for connecting the code combination conductors C1 and CI 4to the lower winding of ringing relay 8|8. The locking circuit for relay 818 may be traced as follows: from ground at armature 888, conductor 128,'armatures 845, 855, 885 and 815 through the winding of relay 818 to battery. Counting relay 888 energizes over the` following circuit: from grounded conductor 89.1, armatures 828 and 838 in multiple, armatures 811, and through the winding of relay 888 to battery. Relay 888, upon energizing, at armature 8| I opens the original energizing circuit of relay 810 and at armature 882 completes the locking circuit for itself independent of armature 881.

In response to the second impulse of the series line relay 898 again deenergizes and again opens the circuit of the impulsing relay 848 which likewise deenergizes. At armature 842 and resting contact relay 848 again completes the circuit for the series relay 858 before the latter relay has had time to deenergize, and also grounds conductor 133 for energizing relay 128 in series with relay 188. This-circuit may be traced from grounded conductor '|33 by way of armature 183 and working contact, through the lower lwinding of relay 188, andthrough the upper winding of. relay 128 to battery. Relay 188 is maintained energized over this circuit and relay 128, upon energizing, at armature 12| prepares a. circuit for reenergizing relay 848 when line relay 888 again 'energizes and at armature 122 opens the locking circuit of relay 1 I8 which now deenergizes. Relay 1 I 8, upon deencrgizing, at armatures 1|3I and 1|4 completes the locking circuit through the lower winding of relay 1,28 as follows: from grounded conductor 891 by way of resting contact and armature 1 I4, armature 122 and working contact, armature 1|3 and through the lower winding of relay 128 to battery.

At the end of the second impulse line relay 888 again energizes and this time completes a circuit for energizing relay 848 from grounded amature also removes ground from conductor 133. In response to the removal of ground from conductor 133 the circuit through the lower winding of. relay 188 is opened and the latter relay thereupon devenergizes. At armature 18| relay 188 opens the last mentioned energizing circuit of relay 848 and prepares a point in the alternate energizing circuit for the same relay, at armature 183 again prepares the circ-uit for relay 1I8, and at armature 184 disconnects ground from conductor 1I8 and connects ground to conductor 188 for energizing counting relay 888 by way of armature 814. Counting relay 888 at armature 88| prepares the circuit extending to the finder group control relay 422, at armature 882 prepares the circuit extending to the finder units relay 388 which, however, is ineffective at this time and is only effective during the dialling of the second digit; at armature 882 prepares the energizing circuit for counting relay 858, at armature 884 completes its own locking circuit, at armature 885 opens the locking circuit of relay 818,r and at armatures 888 and 881 prepares circuits for connecting the ringing relay 8I|I to the combination ring conductors C8 and C2 in case the third digit or the code ring digit is being dialled. The locking circuit for relay 888 extends from grounded conductor 129 by'way of armatures 845, 855 and 884. Counting relay 818 deenergizes and at armature 813 again completes the locking circuit for relay Si, and at armature 818 prepares a point in the locking circuit for counting relay 838. At armatures 814 and 811 relay 818 opens the initial energizing circuits of relays 888 and 888, respectively, but said relays do not deenergize at this time because the saine are maintained energized over their previously traced locking circuits, and at armature 812 opens the prepared circuit for the connector group control relay 432.

In response to the third impulse relays 888 and 848 deenergize and the latter relay at armature 842 again grounds conductor 133. Since relay 188 is in deenergized position the circuit for energizing relay 1|8 is completed through the resting contact of armature 183 from grounded ccnductor 133 and the latter relay upon energizing at armatures 1I3 and 1I4 opens the locking circuit of relay 128 whereupon relay 128 now deenergizes. pares the energizing circuit for impulsing relay 848. At armature 122 relay 128 short circuits the upper winding of relay 188 by way of armature 1l4 and armature 183.

At the'end of the third impulse line relay 898 energizes and at armature 89| completesthe circuit for energizing relay 848. At armature 842 relay 848 disconnects ground from conductor 133 in order to remove the previously traced short circuitv around the upper winding of relay 188. In the same manner as previously described relay 188 now energizes in series with relay 1I8 and relay 188 at armature 184 completes the circuit from grounded conductor 891 for energizing counting relay 858 by Way of operated armature 883. lAt armature 85| relay 858 prepares a circuit for operating connector group control relay 432, at armature 852 prepares the circuit for energizing relay 188 or connector units relay 388, at

armature 853 prepares the energizing circuit of At armature 1I'i relay 1|8 again pre-1 aoeaase counting relay 8M, at amature 854 completes its iii) grounded conductor ile, and at armature 85@ opens the locking circuit of counting relay 86o,

' which now deenerglzes. Relay 864i, upon decriergizing, at armature 86! opens the prepared circuit for the connector group control relay $22, at armature 862 opens the initial energizing. circuit of relay tto, and at amature 865 prepares a point in the locking circuit for relay 81B.

The foregoing cycle of operations of the impulse repeating relays lill, m and l2@ continues until the end of the impulse series. That is, at the start of each odd impulse relay HIB energizes and relay l2@ deenergizes and at the end of each odd impulse relay 'm0 energizes and grounds conductor 'H15 to operate'the counting relay having its circuit prepared by the last actuated counting relay. At the start of each even impulse relay l2@ energizes and causes relay H0 to deenerglze and at the end of each even impulse relay lil@ deenergizes and grounds conductor lil@ to operate the counting relay having its circuit pre pared by the last actuated counting relay. The energizing circuit for the impulsing relay et@ is taken through armatures 7M, Hi and 712i so that on light impulses (Weak impulses received over leaky lines) the circuit to relay te@ cannot be closed until after relay 'iiii or '32@ operates thus insuring the proper operation of the impulse repeating relays. Impulse counting relays u, Bt and 33o, respectively, operate in response to the third, fourth and fth impulses of the series. Each counting relay opensthe locking circuit of the preceding counting relay, prepares the circuit to the succeeding counting relay. Each counting relay prepares the circuit to its asso1 ciated connector group control relay in the same manner as described for counting relay titi?. I

On the sixth impulse counting relay uit@ energizes from grounded conductor M9 by Way oi armature @33, and at armature dit closes its own locking circuit to grounded conductor i129, at armatures ti and $22 switches the generator lead ttt, at armature o23 transfers the operating cir- Vcuit for the connector group control and connector unitsrelays, at armature 824 completes a cir cuit for maintaining relay Siv in operated position from grounded conductor liti, at its er upper armature opens a point in its original en= ergizng circuit after the relay is locked up by way of armature 325. At armature 82s relay t2@ opens the locking circuit of relay 8st since relay 83@ is at this time also energized, at armature @2li prepares circuits for connecting the code ringing combination leads Cl to Ci, inclusive, to the lower winding of relay 8m, and at armature o2@ prepares a pointV in the circuit for connecting relay 8i@ to the mask conductor M2. Relay 36%, upon deenergizing, at armature v138i again prepares the circuit'of counting relay 91d.

0n the seventh impulse of the series relay el@ reenergizes closing its locking circuit at armature 875, opening the locking circuit of relay t3@ at armature tit, preparing the circuit of relay te@ at armature 872, and at armature 8M preparing the circuit of relay 866. Counting relay 83@ deenergizes and at armature 836 completes the circuit from grounded conductor 69T for reenerglzing relay S30 by way of armature 811. Relay 886i operates and closes its locking circuit at arma- .ture 882 and at armature 88! opens the initial energizing circuit of relay B10. Succeeding impulses of the series operate relays 86th, 85d, and 840 in sequence, as previously described. The

` equipment.

l 9 following chart shows the relationship between the impulses dialled, the impulse repeating relays, the impulsing counting relays, and the circuits controlled thereby for-the diu'erent digits.

l Impulsing chart After the last impulse of the series, series relay tot@ deenergizes and at armature 52 opens the lmpulsing circuit to the impulse repeating relays itt, it@ and itt. At armature @E3 relay 6E@ opens the locking circuit through the lower lWinding oi.7 relay @Siti and also removes ground from conductor @Si to open the locking` circuit of counting reiay at@ and the locking circuit for. the operated impulse repeating relays. it armature titi-"t relay t5@ opens the initial energizing circuit oi relay Si, and at the resting contact of armature @5t completes the circuit for energizing the seiected connector relay itt, relay litt, or relay ttt, depending upon the digit dialled.

If the rst digit received is the digit 1 series relay et@ uponl restoring at armature tot opens the circuit ci relay Si and the latter relay upon restoring at armature tot opens-the locking circuit to counting relay tit. At armature tot relay disconnects ground from conductor @di to deenergize relay ott. in response to the deenergization of series relay t5@ the counting re lays @iti and to@ are restored to their normal position without accomplishing any useful func tion. This circuit arrangement is provided to prevent a preliminary impulse from tying up the in case the first digit is the digit 9 series relay tot, upon restoring, at armature tl'closes Athe circuit for energizing relay itt as follows:

from ground by way of armature 638 andv working contact, armature tt 'and resting contact, armature @do and resting contact, armature t'ii, conductor i735, armature 825-3 and working contact,

armature @512, armature si?, conductor "dit, and

through the winding of relay it@ to battery. The digit 9 is only dialled when a trunk connection to another exchange is desired and will be de scribed in detail hereinafter.

If the rst digit is the digit o series relay o, upon restoring, at armature 65d closes the circuit for energizing relay l5@ as follows: from ground at armature @38 over the previously traced circuit to conductor 135, thence by way of arma- G ture @te and 'working contact, armature 8d2, armature t i 5, conductor Tli, and through the wind-- ing of relay it@ to battery. The digit 0 is only diailed when a trunk connection to avdiflerent exchange is desired, and will be'described more fully hereinafter. l

In case theiirst digit dialled is 7 series relay 6W, upon restoring, at armature Bt closes the circuit for energizing relay 801i as follows: from ground at armature 638, over the previously group control relay. 

